DESCRIPTION (Applicant's Abstract): The candidate for this NIMH K02 Independent Scientist Award was trained as an experimental psychologist and has performed empirical research on the visual perception of optic flow and the control of human locomotion. His long-term objective is to integrate work on perception and action in a dynamical account of visual control. Short-term career goals are to develop a strong theoretical component to his research, including modeling the neural processing of optic flow and the dynamics of visual control, and to incorporate research on perceptual-motor learning. The proposed career development plan includes a course sequence in mathematics and control theory, training in neural and dynamical modeling techniques. The award would be used to release the applicant from teaching and administrative responsibilities to devote full time to research and training. The specific aims of the proposed research are to determine how information in optic flow is extracted by the visual system and used to control balance and steering during locomotion. Four interrelated projects are proposed. The first project, on perception of heading, will determine the information used to perceive headings during observer translation and rotation, and in the presence of moving objects, using psychophysical methods. A model of this process will be formalized and tested. A project on visual control of steering will determine whether this information is used to control steering with respect to stationary and moving objects, in a joystick control task. The third project, on visual control of walking, will examine how optic flow is used to control balance and steering during treadmill walking and will model the control dynamics of the perception-action loop. The final project focuses on learning control dynamics and will investigate how an infant in a "baby bouncer" explores and learns to control the dynamics of a simple task, as a model for the acquisition of locomotion. The results would contribute to basic knowledge about the perception of optic flow and the control of locomotion, providing a foundation for clinical research on visual-motor deficits, gait disorders and mobility problems.